Rocket for firing and spreading reflecting material

ABSTRACT

A rocket for spreading reflecting material to achieve a radar echo comprises a rocket body having a rocket motor at one end thereof, and a rocket head containing the reflecting material at the other end thereof. The casing is locked to the rocket body by a locking mechanism which is adapted to be released by gas pressure generated by detonation of a separating charge. The locking mechanism includes an elongated tube adapted to support the reflecting material on its exterior, and operative to selectively form an interior gas channel between the separating charge and the front part of the casing under the control of a valve member.

United States Patent Gustafsson et al.

ROCKET FOR FIRING AND SPREADING REFLECTING MATERIAL Inventors: Melker Emanuel Gustafsson; Yngve Bertil Stradalen; Erik Gustav Ake Zander, all of Karlskoga, Sweden Assignee: AB Bofors, Bofors, Sweden Filed: June 5, 1973 Appl. No.: 367,313

Foreign Application Priority Data June 16, 1972 Sweden 7596/72 US. Cl l02/34.4, 102/37.6, 102/89 Int. Cl F42b 15/00, C06d l/O4 Field of Search 102/37.6, 34.4, 63, 89,

References Cited UNITED STATES PATENTS 7/1949 Jeppson ..102/34.4 8/1962 Schermuly ..102/37.6

7/1963 Jansen et al. l02/37.6 3,143,965 8/1964 La Pointe 3,741,125 6/1973 La Pointe l02/34.4

Primary Examiner-Samuel W. Engle Assistant Examiner-C. T. Jordan Attorney, Agent, or FirmElliott l. Pollock [5 7] ABSTRACT A rocket for spreading reflecting material to achieve a radar echo comprises a rocket body having a rocket motor at one end thereof, and a rocket head containing the reflecting material at the other end thereof. The casing is locked to the rocket body by a locking mechanism which is adapted to be released by gas pressure generated by detonation of a separating charge. The locking mechanism includes an elongated tube adapted to support the reflecting material on its exterior, and operative to selectively form an interior gas channel between the separating charge and the front part of the casing under the control of a valve member.

7 Claims, 6 Drawing Figures PM'ENTED 3EP241974 3. 837. 27 8 sum 1 BF 3 PAIENIED SEPZ 4 I814 SHEUQBFS ROCKET FOR FIRING AND SPREADING REFLECTING MATERIAL BACKGROUND OF THE INVENTION The present invention relates to a rocket for firing and spreading reflecting material, consisting of cut pieces of thread or fibers which after firing and spreading, is specially intended to achieve a radar echo. The rocket comprises a rear propelling part with a rocket motor, and a rocket head containing the material intended to be fired and spread. The rocket head comprises a cylindrical casing, which is provided with a nose cone at its front end.

Rockets of this general type are previously known, in which the spreading of the reflecting material takes place with the aid of a spreading charge, which in conjunction with the spreading operation either blows away the casing around the material or, after the removal of the nose cone, expels the material forwards out of the casing.

A problem involved with these known rockets is that all of the reflecting material will be ejected simultaneously and instantaneously, which has the result that the spreading will not be satisfactory. In order to achieve a desired radar echo, it is necessary to spread the material successively along a portion of the rocket trajectory, which is not possible with the known rockets. A problem in connection with the spreading operation is also to distribute the individual elements of the reflecting material with an appropriate distance between the elements in space, which is of importance if the best possible reflection effect is to be obtained.

SUMMARY OF THE INVENTION The above-mentioned problems have now been eliminated generally by means of a rocket of the aforementioned kind which, according to the present invention, is characterized by the casing being connected with the rocket body by means of a locking mechanism that can be released, and which is arranged to be expelled forwards by means of a separating charge, for uncovering the material to effect spreading of the material through the influence of the air current around the rocket.

The advantage of this arrangement is that not all of the reflecting material will be spread out simultaneously, but instead will be dispersed successively along an appropriate portion of the rocket trajectory, which is achieved by the material, after the casing in which it is enclosed has been blown off, being spread by the influence of the air current around the rocket. Thus, no special spreading charge is used for this purpose.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to the attached drawings, in which FIG. 1 shows a side view of the rocket according to the invention,

FIG. 2 is a partly cut-away side view of the rocket head,

FIG. 3 is a longitudinal section through the part of the rocket which is intended to be blown off in connection with the spreading of the reflecting material,

FIG. 4 is a section, on a larger scale, of a locking device intended to secure the part that can be blown off, before the spreading,

FIG. 5 is a plan view of one of the separating discs which are placed between the different bunches of the reflecting material, and

FIG. 6 is a plan view of a supporting plate arranged in the rocket head.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As will be noted from FIG. 1, the rocket comprises a rear propelling part 1, which contains a rocket motor, and a rocket head 2, containing the reflecting material intended to be spread out. The propelling part 1 does not constitute any part of the invention, and therefore will not be described in detail.

The rocket head 2 shown in FIGS. 2 and 3 comprises an elongate cylindrical casing 3, the front end of which is provided with a nose cone 4. At the joint between the casing 3 and the nose cone 4 there is a fastening plate 5. At the middle of the plate 5, an inner tube 7 is welded, which extends rearvvards coaxially with the cylindrical casing 3, and has practically the same length as casing 3. The tube 7 is provided with openings 9.

The rear end of the casing 3 is mounted around a fastening plate 10, which is provided with internal threads for screwing the plate to the rocket body. The rocket head is sealed off by means of a sealing ring 11 between the casing 3 and the plate 10, in the center of which an outer tube 12, directed forwards, is screwed which encloses the inner tube 7, and has substantially the same length as tube 7. Between the two tubes there is a sealing ring 13, which is mounted in a groove in the inner tube 7. At the front end of the outer tube 12 a supporting plate 14 is mounted, which is guided in relation to the fastening plate 5 by means of a pin 15. The purpose of the plate 14 is to prevent the reflecting material located behind the plate from going along forward when the casing 3 is blown off, and the plate is perforated by means of holes 14a, as shown in FIG. 6. By having different degrees of perforation in the plate 14, different spreading times and, accordingly, different extensions of the reflecting material can be obtained.

In the space between the outer tube 12 and the casing 3 the reflecting material is mounted in the form of a stack, consisting of bunches 16, each of which has the form of a hollow cylinder. The stack is enclosed in four plate segments 16a, which protect the bunches during the separation of the casing 3, to be described, and prevent spreading of the reflecting material before the separation has been completed. Between the individual bunches 16 of reflecting material, separating discs 17 are placed, and a plan view of one of these is shown in FIG. 5. As will be noted from this Figure, the discs 17 are provided with four recesses 18, uniformly distributed around the periphery. Further, the discs are divided diametrically into two equal parts along the line 19. The recesses 18 are intended to enable cutting of the wrappings, e.g. of paper, of the bunches 16. The cuts are made between the segments 17 before the casing 3 is mounted.

FIG. 4 shows a locking mechanism which is intended to retain the casing 3 which can be blown off of the rocket before the spreading of the reflecting material, and which is released under the actuation of a separating charge, so that the casing can be blown off when the material is to be spread. The casing 3 with the nose cone 4 is held in place before firing, by means of the locking mechanism with the aid of the front fastening plate 5 and the inner tube 7 by the locking mechanism in the locked position forming a connection member between the inner tube 7 and the rear fastening plate 10.

The locking mechanism comprises an outer sleeve 20, the front part of which is screwed into the inner tube 7, and the sleeve is thus fixed to this tube. In the sleeve 20 there is a displaceably arranged inner sleeve 21, in the front end of which a locking plunger 22 is fitted. The inner sleeve 21 is held in place in the outer sleeve 20 by means of a radial collar 24, which is directed outwards, and which in the position shown is in contact with the front end of the outer sleeve 20, and which also forms a contact surface for the rear end of a pressure spring 25, the front end of which rests against a washer 26 which, in turn, is in contact with a step in the inner tube 7. The sleeve 21 also has axial gas channels in the form of slots 23.

The locking plunger 22 is retained in the axial position shown in relation to the inner sleeve 21 by means of locking balls 27, which are placed in radial openings in the sleeve 21 and engage in a circumferential groove 28 in the plunger 22. In the front end of the plunger 22 there is an axial recess 29, the purpose of which will be described in more detail in the following.

The rear end of the outer sleeve 20 is made with radial openings, in which locking balls 32 are placed, which engage in an internal, circumferential groove in a securing ring 33, which is pressed into the fastening plate 10. On the hub section of the plate 10, a nut 35 is screwed, which also constitutes a holder for a separating charge 36.

After the firing of the rocket, the separating charge 36 is initiated with the aid of a fuze, not shown, with an appropriate, predetermined delay. The gas pressure behind the plunger 22 then presses this forwards, together with the displaceable inner sleeve 21, against the action of the spring 25. When the step 20 at the rear part of the inner sleeve 21 has passed the balls 32, it is possible for these balls to move radially inwards, and become disengaged from the securing ring 33, whereby the lock between the outer sleeve 20 and the ring 33 is released. The inner sleeve 7 and, consequently, also the casing 3 can thereafter move forwards in relation to the outer tube 12 and the rear, propelling part of the rocket.

When the inner sleeve 21 continues its movement forwards in relation to the outer sleeve 20, the balls 27 will pass the front end of the outer sleeve 20. When this has taken place, the balls 27 can move radially outwards and become disengaged from the groove 28 in the plunger 22. The plunger is thereby released, and under the actuation of the gas pressure continues forwards through the tube 7. When the rear end of the plunger 22 has passed the rear end of the gas channels 23 in the sleeve 21, the gas can pass by the plunger 22 through these gas channels, while the plunger 22 is still guided in the sleeve 21. Because of the gas channels 23, the ejection speed of the plunger 22 will be limited when it leaves the sleeve 21. Because of the plunger 22 having been provided with the recess 29, it is easier for its front end to be deformed, so that the energy of the movement of the plunger at its impact against the plate 5 will be consumed during the deformation of the front part of the plunger.

When the plunger 22 leaves its place in the inner sleeve 21, a coherent gas channel is thus opened through this sleeve and the tube 7. Under the influence of the gas pressure, the inner tube 7 will be urged forwards, and the casing 3 with the nose cone 4 will then also be displaced forwards. The rear end of the casing 3 then leaves the plate 10, and as the casing moves forwards, the plate segments 16a will be uncovered.

When the inner tube 7 has moved forwards so far that the openings 9 have passed the end of the outer tube 12, gas will be permitted to flow out through these openings. This prevents a partial vacuum from arising in the space between the plates 5 and 14, which space will expand when the casing is blown off, since the plate 5 moves forwards, while the plate 14 remains in the position shown in FIG. 2.

When the casing 3 has been blown off and the plate segments 16a have been uncovered entirely, these will quickly fall away, whereby all of the reflecting material is released. Through the air current around the rocket and through the perforations 14a in the plate 14, the material will be spread out continuously. Due to the fact that the separating discs 17 are divided diametrically into two equal parts, these will fall off the tube without impeding the spreading of the material.

Firing tests have shown that, with a rocket of the embodiment described above, it is possible to achieve a radar echo with an extended form, and at the same time as the distribution of the reflecting elements in the material spread out will be improved.

To one skilled in the art, it will be obvious that many modifications of the design described above can be made within the scope of the invention.

We claim:

1. A rocket for spreading reflecting material to achieve a radar echo, said rocket comprising a rocket body having a rocket motor at one end thereof for propelling said rocket along a trajectory, a rocket head containing said reflecting material and disposed at the other end of said rocket body, said rocket head including support means fixedly attached to said body for supporting said reflecting material in place, said rocket head further including a removable casing positioned to enclose said support means and said reflecting material, a locking mechanism for securing said casing to said rocket body in said enclosing position, a separating charge, said locking mechanism including means responsive to the gas pressure generated by detonation of said charge for releasing said locking mechanism and for blowing said casing off said rocket body to expose said reflecting material thereby to cause said material to be spread along a portion of the rocket trajectory under the influence of air currents around said rocket as said rocket is propelled along said trajectory.

2. The rocket of claim 1 wherein said casing is connected to the locking mechanism by means of coaxial tubing means which forms a gas channel between the separating charge and an interior front portion of the casing.

3. The rocket of claim 2 wherein the locking mechanism includes a valve member operative to close the gas channel when the locking mechanism is in its locked position, said valve member being arranged to open the gas channel when said locking mechanism is released.

4. The rocket of claim 3 wherein the locking mechanism includes a first set of locking balls for locking the casing to said body, and a second set of locking balls for locking the valve member in a position closing said gas channel.

means includes a first tubular member affixed to said rocket body in coaxial relation thereto, and a second tubular member affixed to said casing and disposed in coaxial slidable relationship to said first tubular member, said locking mechanism being operative, in its locked position, to prevent slidable movement of said tubular members relative to one another and being operative, in its released position, to permit such slidable movement. 

1. A rocket for spreading reflecting material to achieve a radar echo, said rocket comprising a rocket body having a rocket motor at one end thereof for propelling said rocket along a trajectory, a rocket head containing said reflecting material and disposed at the other end of said rocket body, said rocket head including support means fixedly attached to said body for supporting said reflecting material in place, said rocket head further including a removable casing positioned to enclose said support means and said reflecting material, a locking mechanism for securing said casing to said rocket body in said enclosing position, a separating charge, said locking mechanism including means responsive to the gas pressure generated by detonation of said charge for releasing said locking mechanism and for blowing said casing off said rocket body to expose said reflecting material thereby to cause said material to be spread along a portion of the rocket trajectory under the influence of air currents around said rocket as said rocket is propelled along said trajectory.
 2. The rocket of claim 1 wherein said casing is connected to the locking mechanism by means of coaxial tubing means which forms a gas channel between the separating charge and an interior front portion of the casing.
 3. The rocket of claim 2 wherein the locking mechanism includes a valve member operative to close the gas channel when the locking mechanism is in its locked position, said valve member being arranged to open the gas channel when said locking mechanism is released.
 4. The rocket of claim 3 wherein the locking mechanism includes a first set of locking balls for locking the casing to said body, and a second set of locking balls for locking the valve member in a position closing said gas channel.
 5. The rocket of claim 1 including a spring operative to pre-set said locking mechanism into its locked position.
 6. The rocket of claim 2 wherein said support means includes a plurality of spacer discs disposed in substantially parallel relation to one another along, and in surrounding relation to, said coaxial tube, said reflecting material being packed between said discs and around said tube.
 7. The rocket of claim 2 wherein said coaxial tubing means includes a first tubular member affixed to said rocket body in coaxial relation thereto, and a second tubular member affixed to said casing and disposed in coaxial slidable relationship to said first tubular member, said locking mechanism being operative, in its locked position, to prevent slidable movement of said tubular members relative to one another and being operative, in its released position, to permit such slidable movement. 